This is a sealing technique that is characteristic of the Uzumaki clan. Users produce chains made out of their own chakra, which emerge from their torso. Users control the chains as they extend outwards from their body, most commonly to wrap around targets and restrain them. The chains are extremely durable, enough that even the Nine-Tails would struggle to destroy them. In the anime, in addition to physically binding targets, the chains are said to bind targets' chakra as well. Depending on the number and the length of chains that users intend to produce, they may prefer to initially create only a few chains, which they send underground to split apart and spread around the area as needed, leaving their immediate surroundings uncluttered.
A barrier can be erected between two or more sealing chains, which is quite impregnable: Kushina Uzumaki creates such a barrier to not only prevent the Nine-Tails from escaping a defined area, but also to prevent the Third Hokage from entering it. Because the chains are made of the user's chakra, the chains can be produced anywhere the user's chakra resides. When she was the Nine-Tails' jinchūriki, Kushina used the chains to bind the Nine-Tails within her subconscious, and for this reason she never once lost control of its power. After her death, some of Kushina's chakra was sealed within her son, Naruto Uzumaki, allowing her to produce the chains from his body in order to help him combat the Nine-Tails.
During the Fourth Shinobi World War, Karin awakens the ability to produce similar chains, which she uses to lash against and ultimately destroy a wooden opponent. Orochimaru labels this the same ability as Kushina possessed, but Jin no Sho describes it only as a "glimpse" of Kushina's Adamantine Sealing Chains.